FIG. 1 illustrates an example 2-element prior art power measurement system 100. The power measurement system 100 includes a first voltage measuring element 101A and a second voltage measuring element 101B. First voltage measuring element 101A measures the voltage difference between phase A voltage Va and phase B voltage Vb. Second voltage measuring element 101B measures the voltage difference between phase C voltage Vc and phase B voltage Vb.
The power measurement system 100 includes a first current measuring element 102A and a second current measuring element 102B. First current measuring element it 102A measures the phase A current Ia. Second current measuring element 102B measures the phase C current Ic.
One of the drawbacks with using 2-element prior art power measurement system is that the power measurement system 100 is unable to accurately measure power on an unbalanced load L (i.e., when the phase A current Ia is not equal to the phase B current Ib or is not equal to the phase C current Ic).
FIG. 2 illustrates an example 3-element prior art power measurement system 200. The power measurement system 200 includes a first voltage measuring element 201A, a second voltage measuring element 201B and a third voltage measuring element 201C. First voltage measuring element 201A measures the phase A voltage Va. Second voltage measuring element 201B measures the phase B voltage Vb. Third voltage measuring element 201C measures the phase C voltage Vc.
The power measurement system 200 includes a first current measuring element 202A, a second current measuring element 202B and a third current measuring element 202C. First current measuring element 202A measures the phase A current Ia. Second current measuring element 202B measures the phase B current Ib. Third current measuring element 202C measures the phase C current Ic.
One of the drawbacks with using 3-element prior art power measurement system 200 is that the power measurement system 200 requires three voltage transformers and three current transformers. The power measurement system 200 also requires three voltage measuring channels and three current measuring channels. Therefore, there is added cost associated with utilizing the power measurement system 200.